Attention could play an essential part in the contraction of pelvic floor muscles in stressful situations, meaning that mental distraction may be involved in urinary incontinence. Informed consent was obtained from 20 healthy volunteers. The electromyographic (EMG) activity of the external anal sphincter (EAS) was recorded during voluntary contraction elicited by local stimulation. The trials were performed twice: combined (or not) with a mental distraction task (PASAT), Paced auditory serial additional test. Reaction time, latency between the stimulus and maximum EAS EMG activity, duration of the contraction, maximum EAS EMG activity, and the area under the EAS EMG activity curve were measured. The mental distraction task resulted in a 3.98 times greater reaction time (RT), (P = 0.00001 Wilcoxon’s test). The RT increased from 217 (IQR: 170-270) to 779 msec (IQR: 550-1,025, P < 0.0001) when the EAS contraction was combined with PASAT. However, the maximum EAS EMG activity was weaker during PASAT than in the absence of a mental distraction task: 0.0850 mv versus 0.0701 mv, that is, 1.21 times weaker (P = 0.00077, Wilcoxon's test). Finally, when the two conditions (respectively with and without the mental distraction task) were compared, no significant difference was observed in the area under the EAS EMG activity curve (0.0157 mv sec vs. 0.0162 mv sec, ratio 1.01, P = 0.52).
The study found that the mental distraction task altered voluntary contraction of the pelvic floor muscles.